


Night prank

by imera



Category: Life with Derek
Genre: F/M, Pranks and Practical Jokes, Sleep, Step-siblings
Language: English
Status: Completed
Published: 2019-01-07
Updated: 2019-01-07
Packaged: 2019-10-04 13:30:30
Rating: Mature
Warnings: Underage
Chapters: 1
Words: 911
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17305481
Author URL: https://archiveofourown.org/users/imera/pseuds/imera
Summary: His plan was to turn his step sister into a smurf before the picture day, but things didn't go as planned when Casey started talking in her sleep, saying, and doing, things that shocked Derek.





	Night prank

**Author's Note:**

> No idea how long ago I wrote this, but it's about time I posted it.
> 
> I might continue, but at this moment I made sure it has an ending which is good enough for a one shot

_It is a beautiful prank, one of my best,_ Derek thought as he slowly snuck into Casey’s room late at night. He’d almost fallen asleep himself as he waited for the right time, but held on as he didn’t want to lose the opportunity. Casey would be shocked in the morning when she woke up, her face covered in ink. The best part was that the next day was picture day, so either she would have to spend an hour washing her face, or call in sick as she would never show up looking like a smurf.

Slowly he opened her door, making sure it made no sound as he slipped into the room. It was as always tidy and perfect, her perfection was so annoying it almost made him sick. He fought the urge to mess with her things, he could do it another day. Slowly he moved closer to the bed where she lay, her arms spread, almost as an invitation. Pulling up the bottle of ink from his pocket he remove the cap and slowly moved it in position above her face, ready to put his evil plan into motion when she said something that stopped him.

“Mmmm, Derek.”

At first he was scared she had woken up and caught him in the act, but she was still sleeping, Wanting to be certain she was still sleeping he waited.

“Derek,” Casey moaned.

The tone she said his name in was nothing like any tones she’d spoken his name in, She was confusing him but he knew he should hurry so he could return to his bed. Even though he knew what he needed to do all he did was stare at her as she shifted in her bed.

“Ahhh, yes.”

She was dreaming, and if he wasn’t mistaken it was a sex dream, which shocked him as she was whispering his name. Derek backed away slightly, not certain what to do.

“Mhhhm, yes, yes,” she mumbled as one of her hands moved down under the sheets.

Derek was no idiot and knew exactly what the hand was doing, which was ridiculous as he never imagined her being sexual at all.

“Derek.” she repeated.

Suddenly everything changed for Derek, the desire to destroy her was nowhere to be found as his eyes moved over her sleeping form. The only way he’d seen her up until then was as the intruder, as a bookworm, and an annoying know-it-all, but having knowledge of her dream, of who she dreamt about, he couldn’t help seeing her in a new light.

Suddenly he saw her as another girl he wanted to add to his collection. Seeing her with a new pair of eyes he forgot about what annoyed him, instead he saw her as any other girl, and what he saw was perfect, or close to perfection. Her figure was nice, and her breasts were great, the perfect size, round and perky, and so was her butt, not that he’d really seen it.

Automatically his hand moved down to his cock, rearranging the hardening bulge. He shouldn’t have done it as touching himself only lead to him rubbing his hard cock. Casey was still sleeping and her hand kept moving under the sheet, moaning from time to time. He wondered exactly how her dream was, what he did in it, and if she would remember any of it in the morning.

His attention was brought back to his own situation as his cock begged to be touched, not only rubbed. Derek was about to return to his room when a wicked and twisted thought stopped him. Instead of walking away he pushed his pyjama pants down his legs, revealing his hard cock. It was wrong, he knew it, but he couldn’t help himself, not when she was dreaming about him and touching herself.

Being a teenager meant he wouldn’t last long, not that he thought the scene wouldn’t push him over the edge in an instant. The whole situation made it impossible for him to last long. Maybe it was the taboo which increased his excitement, or maybe it was because he hadn’t had the chance to enjoy himself in a while. Whatever the reason was he found himself having to hold onto her nightstand as he came, his legs trembling beneath him as he could hear her moan deeply. Coming all over her bedsheets.

Slowly the feeling in his legs returned to him and he could finally think clearly, or clearer. He wondered why out of all the nights she could have had a sex dream about him it was that night, the night of his prank.

Derek looked at the mess he’d made and suddenly the prank didn’t interest him any longer. As slowly and quietly as possible he backed out of her room, quickly crawling into his bed.

He knew perfectly well sleeping at once wouldn't be possible so he stared at his ceiling, wondering what to do with the knowledge he possessed. He could use it for evil and blackmail her into doing things for him, if he was really crazy he could even use it to blackmail her into doing something more errotic, but he couldn’t do that without knowing how she really felt about him. Whatever he decided to do with the information he knew right then he needed to keep it a secret, a secret he was certain he would think about a lot at night.


End file.
